Such a big prize leads to a lot of magical thinking. People forget about the odds.
Crime has always been a problem in illegal gambling, and people prey on those gamblers because they know most of them won't go to the police if they get robbed. Gambling involves cash, and that tends to attract criminals.
It's a new form of access to gambling, not a new form of gambling. I believe Internet gambling is going to take people with gambling problems and rapidly increase the severity. They are going to rack up more debt more quickly.
Generally the deeper problems people have, the less they're influenced by game design.